Poor perception of dyspnoea in children with undiagnosed asthma.

The aim of the present study was to establish the differences in dyspnoea perception between children with undiagnosed and diagnosed asthma. A cross-sectional community-based study was performed, which included a parental questionnaire on the child's respiratory health and testing of airway reversibility and bronchial hyperresponsiveness (BHR). "Diagnosed asthma" was defined by a physician's diagnosis of asthma. "Undiagnosed asthma" was defined by the presence of asthma symptoms combined with either airway reversibility or BHR without a physician's diagnosis of asthma. Only children with a positive BHR test were selected for further analysis. Perception of dyspnoea was assessed using the Borg scale and the visual analogue scale (VAS), plotted against the percentage fall in forced expiratory volume in one second and expressed as the slope of the regression line. Of the initial 1,758 participating children, 70 had undiagnosed asthma and 38 had diagnosed asthma. The Borg and VAS slopes in children with undiagnosed asthma were less steep than those of children with diagnosed asthma (Borg: 0.07 and 0.14, respectively; VAS: 0.06 and 0.11, respectively). Among children with bronchial hyperresponsiveness, those without a parent's report of physician's diagnosis of asthma had a worse perception of dyspnoea than children with diagnosed asthma.